Display device having counter-twisting liquid crystal areas and method of operating and manufacturing the same

ABSTRACT

A display apparatus, includes: a first substrate; a gate line formed over the first substrate; a data line traversing the gate line, and comprising a source electrode; a drain electrode facing the source electrode to define a channel area; a passivation layer formed over the data line and the drain electrode, and comprising an organic material; a pixel electrode formed over the passivation layer, and comprising a first stem electrode, at least a part of which is overlapped with the gate line or the data line, and a plurality of first branch electrodes contacted to the first stem electrode where one set of the first branch electrodes extend longitudinally in a direction different from the longitudinal extension direction of another set of the first branch electrodes so as to thereby cause opposed twisting of corresponding liquid crystal material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Korean Patent Application No.2006-0075843, filed on Aug. 10, 2006, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference.

BACKGROUND

1. Field of Invention

Apparatuses and methods consistent with the present disclosure ofinvention relate to Liquid Crystal Display (LCD) devices andmanufacturing methods therefor.

2. Description of Related Art

Generally, a liquid crystal display device is one of the most popularflat panel displays used for computer monitor applications and the like.An LCD device typically includes two display substrates formed as asandwich with liquid crystal material interposed therebetween. Inwardlyfacing surfaces of the two display substrates have electric fieldgenerating electrodes disposed on them such as an array of pixelelectrodes and a common electrode, and the liquid crystal material isinserted between the two display substrates. The liquid crystal materialhas a dielectric anisotropy characteristic that allows it to altertransmission of light therethrough as a function of an electric fieldapplied across the material.

More specifically, the liquid crystal display device controls analignment of liquid crystal molecules in the liquid crystal layer bysupplying a control voltage between the field generating electrodes tothereby apply an electric field of desired intensity and/or polarity tothe liquid crystal material to thereby effect a twisting of the liquidcrystal material and to thus control polarization of light passingthrough the material, thereby displaying a desired image.

The twisted nematic (TN) type of liquid crystal material has been widelyused. In the TN type of liquid crystal display, the field generatingelectrodes are disposed on the counterfacing inner surfaces of the twodisplay substrates, respectively, and liquid crystal polarizationdirectors are arranged in the device to encourage a normal twisting by90° of light passing from the lower display substrate to the upperdisplay substrate. This twisting in combination with polarizationplates, prevents light from passing through, thus presenting a darkpixel area. Then, a twisting voltage is applied between the two fieldgenerating electrodes to change the normal liquid crystal polarizationand allow light to pass through thus changing the dark pixel area into alit one. However, the liquid crystal display device of this TN typetends to have a narrow viewing angle with poor image contrast whenviewed from one side or another of the display rather than head on.Accordingly, a liquid crystal display of an IPS (in-plane switching)type or a PLS (plane to line switching) type has been developed as analternative to the TN type.

However, in the conventional IPS type and the PLS type, since both ofthe two field generating electrodes are disposed on a single displaysubstrate, light transmittance and image visibility become deteriorated.

SUMMARY

The present disclosure provides a display device has improved visibilityand transmittance. According to one aspect of the present disclosure, adisplay device is provided with an improved aperture ratio.

A method in accordance with the disclosure causes liquid crystalmaterial of a same pixel area to twist in opposed directions (i.e.,clockwise and counterclockwise) so as to provide improved imagecontrasting when the image is viewed from one side or another of thedisplay rather than head on. Thus, visibilty from different angles isimproved.

In one embodiment, a display apparatus, comprises: a first substrate; agate line formed over the first substrate; a data line traversing thegate line to define a pixel area, a pixel electrode formed in the pixelarea to have electric field generating branch-electrodes extending insubstantially different directions and a first stem-electrode joiningthe branch-electrodes together; a second substrate facing the firstsubstrate; a common electrode formed over the second substrate, wherethe common electrode may comprise a plurality of secondbranch-electrodes overlapping the pixel area and extending in saidsubstantially different directions where the second branch-electrodesare positioned to be interdigitated relative to the firstbranch-electrodes, and a second stem-electrode connecting the secondbranch-electrodes of the common electrode; and a liquid crystal layerinterposed between the first substrate and the second substrate.

According to an exemplary embodiment, the display apparatus furthercomprises a first parallel alignment layer formed over the pixelelectrode and rubbed in a first direction, and a second parallelalignment layer formed over the common electrode and rubbed in a seconddirection, wherein the first direction and the second directionsubstantially parallel each other, and are opposite to each other.

According to the exemplary embodiment, the first substrate furthercomprises a storage electrode for defining a storage capacitor, where atleast a part of the storage electrode is overlapped with the pixelelectrode.

According to the exemplary embodiment, the liquid crystal layercomprises a liquid crystal with a positive dielectric anisotropy, andthe width of the first branch electrodes and the width of the secondbranch-electrodes are each smaller than about 6 μM. In one embodiment,an electrode gap between an upper set of first branch electrodes and alower, differently directed set of first branch electrodes is about 20μm to 40 μm.

According to another exemplary embodiment, the liquid crystal layercomprises a liquid crystal with a negative dielectric anisotropy, andthe width of the first branch electrodes are each smaller than about 6μm. In one such embodiment, an electrode gap between the upper firstbranch electrodes and the lower first branch electrodes is about 4 μm to14 μm.

According to the exemplary embodiment, a lengthwise direction ofrotation of the upper first branch electrodes has an angle of 0° to 30°clockwise with respect to a lengthwise direction of the gate line whilethe same angle is repeated counterclockwise for the lower first branchelectrodes.

According to the exemplary embodiment, the upper and lower first branchelectrodes are symmetrical with respect to the gate line.

Other aspects of the disclosure appear in the below detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects of the present disclosure will becomemore readily appreciated from the following description of the exemplaryembodiments, taken in conjunction with the accompany drawings, in which:

FIG. 1 is an arrangement diagram illustrating a configuration of aliquid crystal display device according to a first exemplary embodiment;

FIG. 2 is an arrangement diagram illustrating a configuration of a thinfilm transistor (TFT)-supporting substrate of the liquid crystal displaydevice in FIG. 1;

FIG. 3 is an arrangement diagram illustrating a configuration of acommon electrode supporting substrate of the liquid crystal displaydevice in FIG. 1;

FIG. 4 is a sectional view taken along line I-I in FIG. 1;

FIGS. 5 and 6 are sectional views illustrating arrangements of liquidcrystal molecules in an operation of the liquid crystal display deviceaccording to the first exemplary embodiment;

FIG. 7 is a sectional view illustrating a configuration of a liquidcrystal display device according to a second exemplary embodiment;

FIG. 8 is an arrangement diagram illustrating a first stage of amanufacturing method of a thin film transistor according to the firstexemplary embodiment;

FIG. 9 is a sectional view taken along line II-II in FIG. 8;

FIG. 10 is an arrangement diagram illustrating a second stage followingthe first stage in FIGS. 8 and 9;

FIG. 11 is a sectional view taken along line III-III in FIG. 10;

FIG. 12 is an arrangement diagram illustrating a third stage followingthe second stage in FIGS. 10 and 11;

FIG. 13 is a sectional view taken along line IV-IV in FIG. 12;

FIG. 14 is an arrangement diagram illustrating a fourth stage followingthe third stage in FIGS. 12 and 13;

FIG. 15 is a sectional view taken along line V-V in FIG. 14;

FIG. 16 is an arrangement diagram illustrating a fifth stage followingthe fourth stage in FIGS. 14 and 15; and

FIG. 17 is a sectional view taken along line VI-VI in FIG. 16.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments inaccordance with the present disclosure, where the examples areillustrated in the accompanying drawings, and wherein like referencenumerals refer to like or similar elements throughout.

Hereinafter, a liquid crystal display device according to a firstexemplary embodiment will be described by referring to FIGS. 1 to 4.

First, a thin film transistor (TFT) supporting substrate 100 havingtransparency will be described in detail by referring to FIGS. 1, 2 and4.

The TFT-supporting substrate 100 comprises an insulating substrate 110such as one made of a transparent glass and/or transparent plastics, andwhere a plurality of gate lines (GL's) 121 and a plurality of firststorage electrodes (ST's) 131 are formed over the electricallyinsulating and optically transparent substrate 110.

Each gate line 121 (only one shown) transmits a corresponding gatesignal to the gate terminals (124) of a corresponding row of TFT's(i.e., field effect transistors—two shown in FIGS. 1-2), and extendsmainly in a transverse direction in the illustration. The gate line 121includes an end part (not shown) widened for connection with an outerdriving circuit and further widened at parts disposed at respectiveopenings of an adjacent dielectric for connections to a plurality ofgate electrodes 124 by way of extensions protruding upward and throughvias to reach the other layers for connections thereto.

A gate driving circuit (not shown) is provided for generating the gatesignal and it may comprise an integrated circuit (IC) chip mounted on aflexible printed circuit film (not shown) attached to the insulatingsubstrate 110, or directly mounted on the insulating substrate 110itself. Alternatively, the gate driving circuit may be directly formedintegrally on the insulating substrate 110. If the gate driving circuitis directly formed on the insulating substrate 110, the gate line 121may extend to be directly connected to the gate driving circuit.

A first storage electrode 131 is defined to oppose another electrode 135and to thereby define a storage capacitor. The first storage electrode131 extends on the TFT-supporting substrate 100 parallel to the gateline 121, in the horizontal or transverse direction of the illustration.The first storage electrode 131 defines a boundary of a pixel area (PA)together with a corresponding data line 171. That is, the first storageelectrode 131 is formed around an upper edge of the pixel areas shown inFIG. 2 for example (two horizontally adjacent PA's shown). The firststorage electrode 131 is formed between a first pixel area and itsvertically adjacent pixel area (not shown). At least a part of the firststorage electrode 131 is overlapped with a pixel electrode 191. The gateline 121 extends into the pixel area. For example, the gate line 121extends into and through a central part of the pixel area, and dividesthe pixel area into two subareas.

A side of the first storage electrode 131 has an inclined angle of 0° to30° with respect to a lengthwise direction of the gate line 121. Thefirst storage electrode 131 has a symmetrical configuration with respectto an imaginary central line paralleling the gate line 121. For example,the first storage electrode 131 may have a symmetric trapezoidal shape,for example that mirroring the illustrated shape of storage electrode135 in combination with stem electrode 194 c. (See also FIG. 8.) Sincethe first storage electrode 131 is overlapped with the pixel electrode191 (not shown) at an edge of the pixel area, undesirable leakage oflight around an edge of the pixel electrode 191 can be prevented withoutneed for a separate light intercepting member (i.e., a black maskingmatrix).

The first storage electrode 131 may be formed of (patterned from) thesame conductive material layer used for forming the gate line 121. Also,the first storage electrode 131 receives a predetermined voltage such asa common reference voltage.

The gate line 121 and the first storage electrode 131 may be composed ofan aluminum-based metal such as aluminum, an aluminum alloy, etc., or asilver-based metal such as silver, a silver alloy, etc., or acopper-based metal such as copper, a copper alloy, etc., a molybdenumseries metal such as molybdenum, a molybdenum alloy, etc., and similarlyfor chrome, tantalum, titanium, etc.

The gate line 121 and the first storage electrode 131 may have a multilayer configuration comprising two conductive layers (not shown) withdifferent physical properties. One of the conductive layers may comprisea metal having a relatively small resistivity such as an aluminum seriesmetal, a silver series metal, a copper series metal, etc. to reduce asignal delay or a drop of voltage. The other of the conductive layersmay comprise an interface material with a good physical, chemical andelectrical contact properties relative to other materials, especiallyrelative to ITO (indium tin oxide) and/or IZO (indium zinc oxide). Theinterface material may be one such as a molybdenum series metal, chrome,tantalum, titanium, etc. For example, a chrome lower layer and analuminum (alloy) upper layer, and an aluminum (alloy) lower layer and amolybdenum (alloy) upper layer are applied thereto. However, the gateline 121 may comprise other various metals or electric conductors.

Over the gate line 121 and the first storage electrode 131, a gateinsulating layer 140 is provided and it includes a dielectric such as asilicon nitride SiN_(x), a silicon oxide SiO_(x) or the like.

Over the gate insulating layer 140, a plurality of semiconductor islands154 are provided and these may include hydrogenated amorphous silicon(referred to ‘a-Si’), polysilicon or the like. The semiconductor islands154 of respective TFT's overlap the corresponding gate electrode 124 ofthose transistors.

A plurality of ohmic island contact members 163 and 165 are formed overthe island semiconductors 154. The ohmic island contact members 163 and165 may comprise hydrogenated amorphous silicon densely doped as N+ withan n-type impurity such as phosphorus, or a silicide. The ohmic islandcontact members 163 and 165 are disposed to make a source/drain pairover the island semiconductors 154.

The ohmic island contact members 163 and 165 are disposed only betweenthe island semiconductors 154, and the data line 171 and a drainelectrode 175, and reduce a contact resistance therebetween. The islandsemiconductors 154 between the source electrode 173 and the drainelectrode 175 define a non-metalized channel region. Also, the islandsemiconductors 154 have an exposed part not covered by the data line 171and the drain electrode 175.

A plurality of data lines 171 and a plurality of drain electrodes 175are formed over the ohmic island contact members 163 and 165 and thegate insulating layer 140. A plurality of second storage electrodes 135are formed over the first storage electrode 131 and the gate insulatinglayer 140.

The data line 171 transmits a data signal, and extends mainly in aperpendicular direction to cross the gate line 121. The data line 171includes first and second end parts (not shown) widened for connectionwith an outer driving circuit and further parts for coupling with aplurality of source electrodes 173 protruding upward and other layers,or for connection thereto. A data driving circuit (not shown) generatingthe data signal may be mounted on a flexible printed circuit film (notshown) attached on the insulating substrate 110, directly mounted on theinsulating substrate 110 or directly integrated to the insulatingsubstrate 110. If the data driving circuit is directly integrated ontothe insulating substrate 110, the data line 171 may extend to bedirectly connected therewith.

The drain electrode 175 (see FIG. 4) is separated from the data line171, and also spaced-apart from the source electrode 173 while centeringover the gate electrode 124 and the corresponding, channel region 154.The drain electrode 175 includes a first end part 177 widened, and asecond end part having a bar shape, and the second end part issurrounded by the source electrode 173 patterned in a U shape.

One gate electrode 124, one source electrode 173 and one drain electrode175, together with the island semiconductor 154, compose one TFT (thinfilm transistor), and a channel of the TFT is formed to the islandsemiconductor 154 between the source electrode 173 and the drainelectrode 175.

The second storage electrode 135 is formed in the same conductivematerial layer as that of the data line 171 and the drain electrode 175,and may include the same material as the data line 171 and the drainelectrode 175. The second storage electrode 135 extends in a traversedirection to parallel the gate line 121, and is formed to an edge of apixel area. The second storage electrode 135 according to the firstexemplary embodiment of the present invention may be overlapped with thefirst storage electrode 131, and have the shape of an asymmetric half ofa symmetrical trapezoid. A storage capacitance is formed in the regionwhere the second storage electrode 135 and the first storage electrode131 are overlapped with each other. Also, a storage capacitance may befurther formed partially in the region where the second storageelectrode 135 and the pixel electrode 191 are overlapped with eachother.

In one embodiment, the data line 171, the drain electrode 175 and thesecond storage electrode 135 are fabricated so as to include arefractory metal such as molybdenum, chrome, tantalum and titanium, oralloys thereof, and to have a multi layer configuration comprising arefractory metal layer (not shown) and a conductive layer (not shown) ofa smaller resistance. For example, a double layer including a chrome ora molybdenum (alloy) lower layer and an aluminum (alloy) upper layer,and a triple layer including a molybdenum (alloy) lower layer, analuminum (alloy) middle layer and a molybdenum (alloy) upper layer areapplied thereto. However, the data line 171, the drain line 175 and thesecond storage electrode 135 may include other various metals orelectric conductors.

A passivation layer 180 (FIG. 4) is formed over the data line 171, thedrain electrode 175, the second storage electrode 135 and the exposedpart of the island semiconductor 154. The passivation layer 180 mayinclude an organic insulating material with a relatively moderatedielectric constant, and have photo sensitivity. For example, thepassivation layer 180 includes an organic insulating material of acrylseries, and dielectric constant thereof may be 3 to 5. The dielectricconstant thereof may be 3.4 to 4. Also, the passivation layer 180 has athickness of approximately 2.5 μm to 5 μm. Alternatively, thepassivation layer 180 has a thickness of approximately 3 μm.

Since the passivation layer 180 comprising an organic material over thedata line 171 has a relatively small or moderate dielectric constant andis capable of being thickened, the data line 171 and the pixel electrode191 can be sufficiently insulated from each other. Accordingly,interference between the data line 171 and the pixel electrode 191 canbe reduced so that the pixel electrode 191 may be overlapped with thedata line 171 or the gate line 121 rather than being forced to terminateat the position where the data line 171 or the gate line 121 begins.Accordingly, an aperture ratio can be improved because users can view alarger area of pixel electrode.

The passivation layer 180 may have a double layer configurationincluding an inorganic lower layer and an organic upper layer to preventdamage to the exposed part of the island semiconductor 154 withmaintaining an excellent insulating property which an organic layer has.The inorganic lower layer may comprise silicon nitride SiNx or siliconoxide SiOx.

A plurality of contact holes 181 and 183 are formed through thepassivation layer 180 to respectively expose the drain electrode 175 andthe second storage electrode 135, and a contact hole (not shown) isformed through the passivation layer 180 to expose an end part (notshown) of the data line 171. Also, a plurality of contact holes (notshown) are formed through the passivation layer 180 and the gateinsulating layer 140 to expose an end part (not shown) of the gate line121. The contact hole 181 exposing the drain electrode 175 and thecontact hole 183 exposing the second storage electrode 135 areelectrically connected to the pixel electrode 191.

A plurality of pixel electrodes 191 are formed over the passivationlayer 180. The pixel electrodes 191 may include a transparent conductivematerial such as ITO (indium tin oxide), IZO (indium zinc oxide) or thelike.

The pixel electrode 191 includes a plurality of first branch electrodes192 each having a predetermined angle to a lengthwise direction of thegate line 121. The plurality of first branch electrodes 192 aresubstantially parallel one another. Also, the pixel electrode 191includes a plurality of first stem electrodes 194 contacting theplurality of first branch electrode 192.

The plurality of first branch electrodes 192 in a first exemplaryembodiment have a symmetrical configuration with respect to the gateline 121 formed to a central part of the pixel area to be divided intoan upper first branch electrode 192 and a lower first branch electrode192′. A lengthwise direction of the first branch electrode 192 accordingto the first exemplary embodiment of the present invention may have aninclined angle of 0° to 30° with respect to a lengthwise direction ofthe gate line 121. The width of the first branch electrode 192 may besmaller than 6 μm. In one embodiment, the width of the first branchelectrode 192 is about 4 μm. An electrode gap between the first branchelectrode 192 and the first branch electrode 192 may be 20 μm to 40 μm.For example, the electrode gap therebetween may be 31 μm.

The first stem electrodes 194 connect the upper first branch electrodes192 and the lower first branch electrodes 192′. The first stem electrode194 according to the first exemplary embodiment includes a first part194 a, a second part 194 b, a third part 194 c, a fourth part 194 d anda fifth part 194 e. The first and the second parts 194 a and 194 b arerespectively formed at edges of the pixel area, and parallel the dataline 171. The first and the second parts 194 a and 194 b are overlappedwith the data line 171. The third and the fourth parts 194 c and 194 dare respectively formed at edges of the pixel area, and include a firstside paralleling the gate line 121 and a second side having apredetermined inclined angle with respect to a lengthwise direction ofthe gate line 121. For example, the third part 194 c includes a sidehaving an angle of 0° to 30° with respect to a lengthwise direction ofthe gate line 121, and the fourth part 194 d includes a side having anangle of 0° to 30° with respect to a lengthwise direction of the gateline 121. The third and the fourth parts 194 c and 194 d are overlappedwith the gate line 121 and the second storage electrode 135. The fifthpart 194 e is formed to a central part of the pixel area, and includes afirst side paralleling the upper first branch electrode 192, and asecond side paralleling the lower first branch electrode 192. The fifthpart 194 e may have a symmetric trapezoid shape.

Each pixel electrode 191 is physically and electrically connected withthe drain electrode 175 of its corresponding TFT through the contacthole 181, and receives the charge from the drain electrode 175 so as toattain a desired voltage level relative to the common electrode. Also,the pixel electrode 191 fills the contact hole 183 exposing the secondstorage electrode 135 and supplies charge to the second storageelectrode 135.

A first liquid crystal aligning layer 197 is formed over the pixelelectrode 191. This alignment layer 197 according to the first exemplaryembodiment may comprise a parallel type of liquid crystal aligninglayer.

Hereinafter, a common electrode supporting substrate 200 will bedescribed by referring to FIGS. 1, 3 and 4.

As shown therein (see FIG. 4), the common electrode supporting substrate200 includes an electrically-insulating and optically transparentsubstrate 210 composed of a transparent glass and/or transparentplastics or the like.

A light intercepting member 220 is formed over the insulating substrate210. The light intercepting member 220 intercepts light leaking from thepixel area, and may include a first part corresponding to the gate line121 or the data line 171, and a second part corresponding to a thin filmtransistor.

The light intercepting member 220 according to the first exemplaryembodiment may be an island type corresponding to the thin filmtransistor. Accordingly, the data line 171 and the first storageelectrode 131 can prevent a light leakage by applying an organic layerto the passivation layer 180 and superposing the pixel electrode 191over the data line 171 and the first storage electrode 131. The shape ofthe light intercepting member 220 may be changed as deemed appropriate.Also, the light intercepting member 220 may be formed over the thin filmtransistor substrate 100. Here, the light intercepting member 220 may beformed to a layer between the passivation layer 180 and the pixelelectrode 191, and may be provided to be an island type to cover thethin film transistor comprising the island semiconductor 154, the sourceelectrode 173 and the drain electrode 175.

The common electrode supporting substrate 200 includes a plurality ofcolor filters 230 and a planarizing layer 240. The color filter 230includes one of primary colors of red, green and blue, and may extend ina vertical direction. The color filter 230 may be formed over the thinfilm transistor display substrate 100.

The planarizing layer 240 may include a (organic) insulating material,and prevents the color filter 230 from being exposed and supplies aplanar surface. The planarizing layer 240 may be omitted if desired.

A common electrode 250 is formed over the planarizing layer 240. Thecommon electrode 250 may include a transparent conductive material suchas ITO, IZO, etc. The common electrode 250 (FIG. 3) includes a pluralityof second branch electrodes 252 formed between the first branchelectrodes 192 of the pixel electrode 191, and not overlapped with thefirst branch electrodes 192 of the pixel electrode 191. The secondbranch electrodes 252 may substantially parallel each other, and maysubstantially parallel the branch electrodes 192 of the pixel electrode191.

The second branch electrodes 252 according to the first exemplaryembodiment have a symmetrical configuration with respect to the gateline 121 formed to a central part of the pixel area to be divided intoan upper second branch electrode 252 and a lower second branch electrode252. A lengthwise direction of the second branch electrode 252 has anangle of 0° to 30° with respect to a lengthwise direction of the gateline 121. The width of the second branch electrode 252 may be smallerthan 6 μm. In one embodiment, the width of the second branch electrode252 may be about 4 μm. An electrode gap between the second branchelectrodes 252 may be 20 μm to 40 μm. For example, the electrode gapbetween the second branch electrodes 252 may be 31 μm.

According to the first exemplary embodiment, the width of each of thefirst branch electrodes 192 (d₁) and the width of each of the secondbranch electrodes 252 (d₂) may be respectively about 4 μm, theelectrode-to-electrode gap (d3, d₄) between each of the first branchelectrodes 192 may be about 31 μm and the electrode-to-electrode gapbetween each of the first branch electrodes 192 may be about 31 μm.Here, the second branch electrodes 252 may be formed between(interdigitated relative to) the first branch electrodes 192.Accordingly, a horizontal electrode-to-electrode gap (d₅) between one ofthe first branch electrodes 192 and the corresponding second branchelectrode 252 may be about 13.5 μm. An opening 253 is formed between thesecond branch electrode 252 and the second branch electrode 252. Theopening 253 may have a parallelogram shape, and a plurality of openings253 parallel one another.

The common electrode 250 (FIG. 3) includes a second stem electrode 254connecting the upper second branch electrodes 252 and the lower secondbranch electrodes 252′. Since a single layer excluding the opening part253 is used as the common electrode 250, all remaining part of thecommon electrode 250 except the opening 253 and the second branchelectrode 252 may define the second stem electrode 254.

The second stem electrode 254 according to the first exemplaryembodiment includes a first part 254 a, a second part 254 b, a thirdpart 254 c, a fourth part 254 d and a fifth part 254 e. The first andthe second parts 254 a and 254 b parallel the data line 171, and areoverlapped with the data line 171. The third and the fourth parts 254 cand 254 d have shapes similar to the first storage electrode 131, andare overlapped with the first storage electrode 131. The fifth part 254e is formed to a central part of the pixel area, and includes a firstside paralleling an upper area of the second branch electrode 252, and asecond side paralleling a lower part of the second branch electrode 252.The fifth part 254 e may have a trapezoid shape, and is overlapped withthe second storage electrode 135.

The common electrode 250 receives a common reference voltage from theoutside.

An upper liquid crystal aligning layer 260 is formed over the commonvoltage 250. The alignment layer 260 according to the first exemplaryembodiment may comprise a parallel type alignment layer.

Hereinafter, an operation of a display device according to the firstexemplary embodiment will be described by referring to FIGS. 1, 4, 5 and6. FIGS. 5 and 6 are sectional views illustrating arrangements of liquidcrystal molecules when a liquid crystal display device according to thefirst exemplary embodiment is operated.

The pixel electrode 191 receiving a data voltage generates an electricfield together with the common electrode 250 receiving a common voltage,and determines a direction of orientation of liquid crystal molecules ofthe liquid crystal layer 300 positioned between both electrodes 191 and250. Polarization of light transmitted through the liquid crystal layer300 varies depending on the direction of orientation of the liquidcrystal molecules.

The liquid crystal molecules of the liquid crystal display deviceaccording to the first exemplary embodiment have positive dielectricanisotropy. The alignment layer 197 of the thin film transistor displaysubstrate 100 is rubbed in a first direction substantially parallelingthe gate line 121, and the alignment layer 260 of the common electrodedisplay substrate 200 is rubbed in a second direction paralleling thefirst direction and opposite to the first direction.

When a twisting voltage is not supplied, the liquid crystal moleculesare aligned to be substantially parallel to surfaces of the substrates110 and 210, and a major axis of the liquid crystal moleculessubstantially parallels the rubbed direction. The rubbed direction andthe first branch electrodes 192 and the second branch electrodes 252form a predetermined angle θ to each other as shown. Accordingly, theliquid crystal molecules are normally inclined at a predetermined firstangle with respect to the first and the second branch electrodes 192 and252 to have an initial twisted angle θ. The initial twisted angle isdefined as an angle between the rubbed direction and a lengthwisedirection of the branch electrodes, or an angle between the rubbeddirection and the branch electrodes. The initial twisted angle is biggerthan 0°, and equal to or smaller than about 30°.

Referring to FIG. 4, when a twisting voltage is supplied, an electricfield is formed between the pixel electrode 191 and the common electrode250. Flux lines of an electric field are formed between the first branchelectrodes 192 of the pixel electrode 191 and the second branchelectrodes 252 of the common electrode 250, and corresponding lateralfield components and vertical field components are concurrently formed.Since the lateral field components prevail, the liquid crystal moleculesrotate mainly on a plane paralleling the substrates to selectivelydisplay on and off states (light transmitting or not transmitting statesor partial states in between).

An upper optical polarizing plate and a lower optical polarizing platemay be attached to the respective TFT and CE supporting substrates.Here, a transmission axis of the upper polarizing plate and atransmission axis of the lower polarizing plate may be perpendicular toeach other. When a twisting voltage is not supplied, a polarizingdirection of light transmitted through the liquid crystal is not changedby the liquid crystal material so that a dark state is displayed. When atwisting voltage is supplied, a polarizing direction of lighttransmitted through the liquid crystal is changed by thevoltage-reoriented liquid crystal material so that a brightened state isdisplayed.

Referring to FIGS. 5 and 6, when a twisting voltage is supplied, liquidcrystal molecules positioned to an area corresponding to the upperbranch electrodes 192 and 252 rotate clockwise (FIG. 5) by the initialtwisted angle, and liquid crystal molecules positioned to an areacorresponding to the lower branch electrodes 192 and 252 rotatecounterclockwise (FIG. 6) by the initial twisted angle. Accordingly, twoside-by-side domains of light repolarization are formed, and visibilityin a right-and-left direction can be improved.

Alternatively, liquid crystal molecules with a negative dielectricanisotropy may be used. Here, the liquid crystal molecules may bealigned in a vertical direction paralleling the data lines 171 a and 171b. Also, the width of the first branch electrode 192 may be smaller thanabout 6 μm. The width of the first branch electrode 192 may be about 4μm. Also, an electrode gap between the first branch electrode 192 andthe first branch electrode 192 may be 4 μm to 14 μm, and may be 11 μM.

The width of the second branch electrode 252 may be smaller than 6 μm.In one embodiment, the width of the second branch electrode 252 is about4 μm. Also, an electrode gap between the second branch electrode 252 andthe second branch electrode 252 may be 4 μM to 14 μm. For example, theelectrode gap therebetween may be 11 μm.

Alternatively, the width of the first branch electrode 192 and the widthof the second branch electrode 252 may be respectively 4 μm and 4 μm,the electrode gap between the first branch electrode 192 and the firstbranch electrode 192 may be 11 μm, and the electrode gap between thesecond branch electrode 252 and the second branch electrode 252 may be11 μm. Here, the second branch electrode 252 may be formed between thefirst branch electrodes 192. Accordingly, an electrode gap between thefirst branch electrode 192 and the second branch electrode 252 may beabout 3.5 μm (equals 4.0 minus 0.5).

Hereinafter, a liquid crystal display device according to a secondexemplary embodiment will be described by referring to FIG. 7.

FIG. 7 is a sectional view illustrating a configuration of a liquidcrystal display device according to a second exemplary embodiment.

As shown in FIG. 7, a thin film transistor display substrate 400 of aliquid crystal display device according to a second exemplary embodimenthas roughly the same configuration as the thin film transistor displaysubstrate shown in FIGS. 1 to 6. However, the common electrode displaysubstrate 500 according to the second exemplary embodiment has adifferent configuration. Hereinafter, a difference will be described.

The common electrode display substrate 500 includes an insulatingsubstrate 510 including a transparent glass, plastics or the like. Alight intercepting member 520 is formed to be an island typecorresponding to a thin film transistor over the insulating substrate510. The light intercepting member 520 may have various shapes asnecessary. Also, the light intercepting member 520 may be formed overthe thin film transistor display substrate 400. Here, the lightintercepting member 520 may be formed to a layer between a passivationlayer 480 and a pixel electrode 491, and may be provided to be an islandtype to cover the thin film transistor comprising a semiconductor 454, asource electrode 473 and a drain electrode 475.

The common electrode display substrate 200 includes a plurality of colorfilters 530 and a planarizing layer 540. The color filter 530 includesone of primary colors of red, green and blue, and may extend in aperpendicular direction. The color filter 530 may be formed over thethin film transistor display substrate 400.

A common electrode 550 is formed over the planarizing layer 540. Thecommon electrode 550 according to the second exemplary embodiment of thepresent invention may be formed in a single planar shape without apattern for forming an electric field. Accordingly, static electricityin the liquid crystal display device can be discharged through thecommon electrode 550 having the planar shape, thereby reducing a staticelectricity strain because there are no points of peaked fieldintensity.

An electric gap, an electrode width and a rubbed direction of the liquidcrystal display device according to the second exemplary embodiment mayhave the same configurations as the liquid crystal display device shownin FIGS. 1 to 6.

Hereinafter, a manufacturing method of a thin film transistor accordingto a first exemplary embodiment will be described by referring to FIGS.8 to 17.

FIG. 8 is an arrangement diagram illustrating a first stage of amanufacturing method of a thin film transistor according to a firstexemplary embodiment of FIG. 1 where FIG. 9 is a sectional view takenalong line II-II in FIG. 8, FIG. 10 is an arrangement diagramillustrating a second stage following the first stage in FIGS. 8 and 9,FIG. 11 is a sectional view taken along line III-III in FIG. 10, FIG. 12is an arrangement diagram illustrating a third stage following thesecond stage in FIGS. 10 and 11, FIG. 13 is a sectional view taken alongline IV-IV in FIG. 12, FIG. 14 is an arrangement diagram illustrating afourth stage following the third stage in FIGS. 12 and 13, FIG. 15 is asectional view taken along line V-V in FIG. 14, FIG. 16 is anarrangement diagram illustrating a fifth stage following the fourthstage in FIGS. 14 and 15, and FIG. 17 is a sectional view taken alongline VI-VI in FIG. 16.

First, referring to FIGS. 8 and 9, a conductive material layer is formed(i.e., blanket deposited) over the insulating substrate 110 including atransparent glass, plastics or the like. Then, a plurality of gate lines121 including the gate electrode 124, and a plurality of first storageelectrodes 131 are lithographically formed by patterning with a dryetching method and/or a wet etching method.

The gate line 121 includes a metal layer, and may include a single layeror multi layers.

Then, referring to FIGS. 10 and 11, the gate insulating layer 140including silicon nitride SiNx, an amorphous silicon (a-Si) layer (notshown), and a doped amorphous silicon layer (not shown) are formed overthe gate line 121 and the first storage electrode 131. Then, thesemiconductor 154 and the ohmic contact layer 164 are formed bydry-etching or wet-etching the amorphous silicon (a-Si) layer and thedoped amorphous silicon layer

Then, referring to FIGS. 12 and 13, a conductive layer is formed overthe gate insulating layer 140 and the ohmic contact layer 164. Then, thedata line 171 including the source electrode 173, the drain electrode175 and the second storage electrode 135 are formed by dry-etching orwet-etching the conductive layer. Then, the ohmic contact layer 164 ispatterned under the mask of the source electrode 173 and the drainelectrode 175 to form the ohmic contact member 163 and 164. Accordingly,the semiconductor 154 is exposed between the source electrode 173 andthe drain electrode 175, and the channel area is formed.

Then, referring to FIGS. 14 and 15, an organic insulating layer iscoated over all surface of the substrate by a slit coating method or aspin coating method to form the passivation layer 180. Alternatively, toprotect the exposed semiconductor 154, an inorganic insulating layercomprising silicon nitride SiNx may be deposited over all surface of thesubstrate by a chemical vapor deposition (CVD) before the organicinsulating layer is formed. Then, a plurality of contact holes 181 and183 are formed by etching the passivation layer 180 by a photo process.

Then, referring to FIGS. 16 and 17, a transparent conductive materialsuch as ITO or IZO is deposited over the passivation layer 180 by asputtering method, and then is patterned to form the pixel electrode191. Here, the contact hole 181 on the drain electrode 175 is filledwith the transparent conductive material to electrically connect thedrain electrode 175 and the pixel electrode 191. Also, the contact hole183 on the second storage electrode 135 is filled with the transparentconductive material to electrically connect the second storage electrode135 and the pixel electrode 191. Then, the alignment layer is formedover the pixel electrode 191. Then, the alignment layer is rubbed in thefirst direction substantially paralleling the gate line 121.

The common electrode display substrate may be manufactured by afollowing method.

A light intercepting member is formed over an insulating substrateincluding a transparent glass and/or transparent plastic or the like.The light intercepting member may be formed in an island typecorresponding to the thin film transistor.

The color filter having red, green and/or blue coloration attributes forexample is formed over the light intercepting member. After coating thesubstrate with a photo sensitive material comprising dyes or pigmentover, the photo sensitive material is patterned by a photo-lithographyprocess to form the color filter. For example, a red color filtermaterial is laminated over all substrate, and is exposed and developedto form a red color filter. A green color filter and a blue color filterare formed by the same method.

Then, the planarizing layer is further formed over the color filter. An(organic) insulating material is laminated over all substrate formedwith the color filter to form the planarizing layer.

Then, the common electrode is formed over the planarizing layer. Atransparent conductive material such as ITO or IZO is deposited over allsubstrate by a sputtering method, etc., and then is patterned to formthe common electrode by a photo etching method. If the common electrodewithout a pattern for forming an electric field is formed, thepatterning process may be unnecessary.

Then, the alignment layer is formed. Then, alignment layer is rubbed inthe second direction paralleling the first direction and oppositethereto.

As described above, the embodiments provide a liquid crystal displaydevice employing an organic insulating layer for a passivation layer,and overlapping a pixel electrode with a data line, thereby improvingthe aperture ratio.

Also, a gate line is disposed in a central part of a rectangular pixelarea, a storage electrode is formed at an edge of the rectangular pixelarea corresponding to a light leakage blocking part, and a first storageelectrode and a second storage electrode are overlapped with each otherto adjust an electric capacitance of a storage capacitor, said placementof the storage capacitor parts at the edges thereby preventing apertureratio from being reduced due to the presence of the storage capacitor.As understood by practitioners, aperture ratio generally refers to theamount of light passed through the display panel when looking at ithead-on as compared to the amount of light striking the panel frombehind. Use of a black matrix with wide stripes can reduce the apertureratio. Use of a pixel-electrode with an opaquely obstructed surface areacan reduce the aperture ratio. Unlike the actual aperture ratio, the“apparent aperture ratio” may define the amount of image generatingefficiency when viewing the display at an angle other than head on. Thepresent disclosure provides for improvements of both the actual apertureratio and the “apparent” aperture ratio.

Also, a data line, and first and second storage electrodes are formed tobe overlapped with a light leaking area of a pixel electrode, therebyomitting a light intercepting member for an area in which the data line,and the first and second storage electrodes are formed.

Although a few exemplary embodiments have been shown and described, itwill be appreciated by those skilled in the art after reading thepresent disclosure that changes may be made in these embodiments withoutdeparting from the principles and spirit of the disclosure.

1. A method of operating a liquid crystal display (LCD) comprising:selectively causing liquid crystal material of a same pixel area totwist in opposed directions so as to provide improved image contrastingwhen the image is viewed from one side or another of the display ratherthan head on.
 2. The method of claim 1 wherein liquid crystal materialin a first half of the pixel area is selectively twisted clockwise inresponse to application of a twisting voltage and liquid crystalmaterial in a second half of the pixel area is selectively twistedcounterclockwise in response to said application of the twistingvoltage.
 3. The method of claim 2 wherein a plurality of pixel areas arearranged as horizontal rows and vertical columns and said first andsecond halves of the each pixel area are disposed in a corresponding oneor another of upper and lower halves of the corresponding row of thepixel area, thereby causing said clockwise and counterclockwise twistingto occur respectively in a corresponding one or another of upper andlower halves of the corresponding row. 4-37. (canceled)